Lock stitch sewing machine



23, 1940. HOPKINS V 2,197,801 LOCK STITCH SEWING MACHINE Filed Dec. 6, 193a 2 Sheets-Sheet 1 Fig.1

April 1940- N. F. HOPKINS LOCK STITCH SEWING MACHINE Filed Dec. 6, 1938 2 Sheets-Sheet 2 ent'm."

Patented Apr. 23, 1940 2,197,801 I Loo s'rrron SEWING. MACHINE Nathan F. Hopkins, Rockland, Mass., assignor to UnitedShoe'Machinery Corporation, Borough a corporation of New 7 Application, December s, 1938,, Serial No. 244,214

r 40mins. (o1.1 12 3s)'- I The present inventionirelates to lock stitch sewing machines, andlmore particularly to. lockstitch sewing machines, the stitch f orming devices of which comprisea curved hook needle and a rotary loop taker in the form of a rotary hook, whichloop taker acts to cast the loops oineedle thread over a locking thread case without itself passing bodily through theloops, and in so doing, imparts a twist of 180 degrees to each needle loop as it passes over'the thread case.

Awell-known. machine of :this type is disclosed in the patent to Ashworth=No. 1,169,909 dated February 1, 1916.

Asfully illustrated anddescribed in the patent to Ashworth above referred to, the rotary hook of a machine of thisv type is provided with a loop entering beak and, during its revolution, the hook carries the leg of the loop w hich is engaged by the needle hook and which leads ,to the inner surface of the beak and which, may be conveniently termed the inner .leg of the loop, back of the thread case, while the other leg of theloop which. leads fromthe workto the outer surface of the beak and which may conveniently be termed the outer leg of the loop is carried across the exposedend of the thread case. During this. operation the inner .leg of the needle loop is lifted fromthe needle hook,

and the outer leg of the loop is swung across and in front of the end of the needle. At this time the needle guide is near the outer end of the needle and, in orderjto prevent the outer leg of the needle loop from being caught on the needle guide, the guide is customarily provided, as illustrated in the patent, with a projection extending laterally at the'side of the needle towards which the work is fed. .In the operation of this type of machine, however, difficulty has been. experienced in timing the movements of the needle guide withsufiicient accuracy so as toprevent the outer leg of the-needle loop from being caught in the open hook of the needle,

and at the same time leave the hook: uncovered so as to permit theescape. from the hook of the inner leg, of the loo-p. This difficulty has always been experienced in the use of machines of this type, but hasbecome especially noticeable since the adoption of so-called increased capacity locking thread caseswhich have an increased thickness and, consequently, require a greater spreading of the needle loop in passing aroundv the thread case. I

An object of the present invention is to overcome the difficulty above noted, and remove from machines of this type any liability of the outer hook. g I To still further improve the operation of this leg of the needle loop. being Caught on the hook I I of the needle With this object in View, a featureof the invention contemplates the provisionof a guardat one Side of the open needle hook arranged to engage the outer leg of the to extend parallel to the needle at one side of the open -needlehook when the needle guide is near the outer end of the needle, said projection being'shaped to engage and deflect the outer leg of the needle loop away from the open hook of the needle while leaving the hook exposed at the side oppositefthe projection to permit the inner leg of the needle loop to be lifted from the needle type of lock stitch sewing machine, a feature of the present invention contemplates. the provision on the rotating loop taking hook, of a projection which is. arranged to engage the inner leg of the needle loop and force it out of the needle hook. This feature of the invention is particu larly applicable to a machine provided with the. I

so-called locking thread case of increasedcapacity. *,Conveniently the projection on the ro.-

tating o k ay be located at the base of the loop entering beak.

The several features of the present inventio will be clearly understood from an inspectionof the accompanying drawings in which Fig. 1 is a view in front elevation of so much of alock stitch sewing machine as is necessary to illustrate, the connection of the invention therewith;

Fig. 2 is a detail view in front elevation of a' needle guide provided with a guard for the nee dle hook and illustrating the manner in which the guard is engaged by the outer leg of the needle loop; Fig. 3 is a sectional view on an enlarged .scale,.taken on the line 3--3 of Fig. 2; Fig. is aview in side elevation of theparts illustrated in Fig. 2; Fig. 5 is a. detail view illustrating in side elevation the needle guide with its guard, the rotary loop taker, and the locking thread case, these parts, together with the needle and shuttle threadsbeing shown in the.

positions they assume just before the beak off the loop taker enters the needle loop; Fig. 6"

is a detail plan View of certain of the parts illustrated'in Fig. 5; Fig. 7 is a view similar to Fig. 5 with the parts in positions they assume after the beak of the loop taker has entered the needle loop and after the outer leg of the needle loop has been swung against the guard on the needle guide; Fig. 8 is a plan view of the parts illustrated in Fig. 6, after the parts have assumed the positions illustrated in Fig. '7; Fig. 9 is a view similar to Fig. 5 with the parts in the positions they have assumed after the loop taker has rotated sufficiently to carry the outer leg of the loop out of engagement with ithe guard on the needle guide and beyond the planeof the needle; and Fig. 10 is a View similar to Fig. 6 but with the parts in the positions illustrated in Fig. 9.

As illustrated in the drawings, the invention is embodied in a machine which, except as hereinafter described, is the same in all essential particulars as the machine of the Ashworth patent hereinbefore referred to. The rotating hook of themachine is indicated at 2, the locking thread case at i, the curved hook needle at 6, the needle guide at 8, and the loop spreader at it. These parts are arranged and actuated as in the machine of the Ashworth patent, the rotary hook being located in a plane at right angles to the plane of operation of; the needle and the open end of the rotary hook and theclosed end of the locking thread case being directed towards the needle. The beak of the rotary hook is indicated at l2 and the shoulder or rib on the. outside of the hook which engages the outer leg of the needle loop and assists in passing this leg of the loop across the closed end of the thread case is indicated at M. The thread case 4 illustrated in the drawings is a so-called increased capacity thread case, and is somewhat thicker than the thread case illustrated in the Ashworth patent. As a consequence, the needle loop is spreadby the rotary hook to a greater extent than in the Ashworth machine, and to facilitatethis action, the beak I2 of the hook is somewhat. blunter and the shoulder I4 is more nearly parallel to the axis of the hook. The manner in which the needle loop is passed over the thread case is clearly illustrated in Figs. 5 to 10 inclusive. Before-the beak of the rotary hook enters the needle loop, the loop has been spread by the joint action of the hook needle 6, and the loop spreader, as

- indicated in Fig. 5. As the beak, enters the loop,

the leg of the loop, indicated at l6, leads to the inner surface of the beak, and the. other leg of the loop, indicated at 18, leads to the outer surface of the beak. For convenience, the legs l6 and W of the loop may be termed the inner and outer legs of the loop. As the hook continues its rotation, the inner leg of the loop is removed from the hook of the needle and carried upward inside of the hook while the outer leg of the ,loop is engaged by the shoulder 14 and forced I to the other. This movement of the outer leg of the loop brings it close to the end of the needle, the tendency of this leg of the loop being .to move in a path intersected by the end of the needle. To avoid any possibility of the outer leg of the loop being caught on the barb of the needle,

. a guard is provided which, in the construction illustrated, comprises a projection 20 formed on .needle while leaving the needlehook free to the needle guide 8 and arranged to extend into the path of the outer leg of the needle loop at the side of the needle remote from the axis of the rotary hook. The projection extends parallel to the needle to a position slightly beyond the.

needle barb and is cutaway on the side next to the needle, as indicated at 22 in Figs. 6, 8 and 10, so as to leave the hook'of the needle sufliciently exposed to permit the removal from the hook of l the innerleg of the needle loop. The outer surface of the projection 20 is curved and so shaped that when it is engaged by the outer leg I8 of the in a satisfactory manner to suppport the needle close toitsouter end and at the same time efl'ectually prevent the engagement of the outer leg of the needle loop with the needle barb, while permitting the inner legof the needle loop to be removed from the needle hook. Also, the provision of the guard 20 on the needle guide per.. mits the beak and other parts of the rotary hook to be shaped and arranged in the most advantageous manner to operate on the needle loop when the machine is fitted'with a thread case of increased capacity; I I

7 To still further facilitate the handling of the needle loop, particularly with a thread case of increased capacity, the rotating hook is provided with a projection indicated at 24 which is ar-v ranged to engage the inner leg of the needle loop and force it from the needle hook. In (the construction illustrated, the projection 24 is located at the base or rear end of the beak of the hook.

The nature and scope of the invention having been indicated, and an embodiment of the several features of the invention having been specifically described, what is claimed is:

1. A look stitch sewing machine having, in comof the beak behind the thread case and the leg of the loop extending from the work to the outer 1 surface of the beak across the exposed end of the thread case, and a guard at one side of the open needle hook arranged to deflect the outer leg of the loop away from the needle hook.

2. A look stitch sewing machine having, in combination, stitch forming devices including a curved hook needle,'a locking thread case having an exposed end directed towards the needle, a rotary loop taker acting to.twist each loop of needle thread and pass it about the thread case,

said loop taker being provided with a loop entering beak and acting tocarry the leg of the loop extendingfrom the needle to the inner surface of the beak behind the thread case and the leg of the loop extending from the work to theouter surface of the, beak across the exposed end of the thread case, and aneedle guide provided with means for deflecting the outer leg of the needle loop 'away from the open hook of the release the inner leg of the loop.

3. A look stitch sewing machine having, in combination, stitch forming devices including a curved hook needle, a locking thread case having an exposed end directed towards the needle, a rotary loop taker acting to twist each loop of needle thread and pass it about the thread case, said loop taker being provided with a loop entering beak andacting to carry the leg of the loop extending from the needle to the inner surface of the beak behind the thread case and the leg of the loop extending from the work to the outer surface of the beak across the exposed end of the thread case, and a needle guide provided with a projection arranged to extend parallel to the needle at one side of the open needle hook and deflectv the outer leg of the needle loop away from the open hook of the needle while leaving the hook exposed at the other side to permit release of the inner leg of the loop by the needle.

4. A'lock stitch sewing machine having, in combination, stitch forming devices including a curved hook needle, a locking thread case having an exposed end directed towards the needle, a rotary loop taker acting to twist each loop of needle thread and pass it about the thread case,

said loop taker being provided with a loop entering beak and acting to carry the leg of the loop extending from the needle to the inner surface of the beak behind the thread case and the leg of the loop extending from the work to the outer 

